Prosthetic knee replacement involves placing a metallic prosthesis at the end of the femur and tibia. The surgical preparation requires making one cut on the tibia, and a number of cuts on the femur using traditionally available tools.
However, a significant proportion of patients who undergo knee replacement surgery have unsatisfactory results. This leads to patients returning with pain, complaints etc, which in turn clogs up waiting lists, leads to pressure on knee surgeons who are overwhelmed with patients, and frequently leads to patients undergoing repeat replacement surgeries. Because knee surgeons are often under severe time pressure, quality control is lost, leading to still more unsatisfactory results from surgery.
One of the main reasons for this is failure to adequately balance soft tissues, (in particular lateral and medial ligaments) of the knee during surgery—if ligaments are not appropriately balanced, even if the bony cuts are made correctly (such that they appear pleasing on X-ray), the patient may experience extremely significant pain if a ligament(s) is overly tensioned as a result of the procedure, or may experience lessening function of the knee if a ligament(s) is loosened excessively.
Frequently ligament(s) are released during knee replacement procedures. This is done by making small releases to the ligament to loosen it from the bone. Unfortunately ligaments are often released too much, or too little, and many operations are conducted with little control over ligament balancing. Often this is left simply to the desire of the surgeon, with little or no templatized control. As stated, even if bony cuts appear pleasing on an x-ray, overly tensioned ligaments, or overly loosened ligaments, may lead to unsatisfactory results for a patient and may require repeat surgery. Repeat surgery has lower likelihood of success, thus further aggravating waiting lists and pressure on surgeons.
Presently available devices allow ligament balancing based on changes to femoral rotation. No tool, instrument, device, or assembly is available that can balance lateral and medial gaps appropriately during a procedure and appropriately align the prosthesis in extension and flexion by altering the bony cuts and/or ligaments, within acceptable limits, in an integrated fashion. No such instrumentation could simultaneously guarantee correct gap measurement between tibial and femoral resection so that the prosthesis can be correctly and appropriately fitted.
Until an industry standard is achieved via correct instrumentation and measuring, unacceptable results for knee replacement surgery will continue, and little quality control, especially globally across the knee replacement industry, will be achieved, which will lead to further problems for patients, knee surgeons, and health systems.